Two-dimensional perovskites as sensitive strain sensors

Two-dimensional (2D) organic-inorganic lead halide perovskites have attracted intensive attention for optoelectronic applications. Principally, strain-induced octahedral distortion in these materials may open up new application scope through modulation of carrier transport. However, they have never been explored as strain sensors. Moreover, traditional strain sensors are troubled by their limited sensitivity at a low strain ratio (<20%), which restricts their use to detect barely visible impact damage. Here, for the first time, we assembled a two-dimensional perovskite (C4H9NH3)(2)PbBr4 into a strain sensor, providing a high sensitivity (gauge factor similar to 141) at an ultralow strain ratio of 0.16% and reversible stretchability. BA(2)PbBr(4) has a positive Poisson's ratio, and its carrier mobilities monotonously decrease upon applying strains. As a prototype, we have integrated this BA(2)PbBr(4) strain sensor into a wearable sensor and successfully detected the motion of finger bending and running.